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Interleukin-2 (IL-2) is a cytokine involved in the development and maturation of the subsets of T cells, critically associated with the progression of several immune-related diseases (e.g. liver disease, bowel disease). Interestingly, a recent study suggests that coffee may contain several compounds to inhibit IL-2 expression in activated T-lymphocytic cells. However, there is little information about the potential effects of several coffee compounds (e.g. kahweol, cafestol, trigonelline, niacin and chlorogenic acids) on IL-2 expression in activated T-lymphocytic cells. Therefore, in this paper, their effects on IL-2 expression were evaluated in PHA/PMA-activated lymphocytic Jurkat cells. Among the tested compounds, only kahweol and cafestol were able to reduce IL-2 production significantly in the cells (p < 0.05). However, the inhibition of kahweol was a bit stronger than cafestol. Therefore, the molecular mechanism underlying the IL-2 inhibition was investigated using kahweol. Kahweol (≤ 20 µM) was able to inhibit the phosphorylations of ERK and c-Fos (p < 0.05) with little effects on p38 and JNK phosphorylations in the Jurkat cells. Subsequently, the inhibition of ERK/c-Fos led to the reduction of IL-2 mRNA expression in the Jurkat cells. In summary, the data suggest that kahweol may be a potential coffee compound to reduce IL-2 production via inhibiting the phosphorylations of ERK/c-Fos in PHA/PMA-activated lymphocytic Jurkat cells. [ABSTRACT FROM AUTHOR]

The control of peripheral lymphocyte numbers is a fundamental aspect of the immune system. Regulatory T cells are involved in the suppression of autoimmune, antitumor, allergic, and other inflammatory responses, as well as in facilitating graft acceptance. In this paper, we discuss whether the control of homeostatic proliferation is another facet of the immune system that is controlled by regulatory T cells. A review of the published data connecting regulatory T cells with the control of homeostatic proliferation indicates that several key questions remain open. One of these relates to the stage at which regulatory T cells could play a role (i.e., T-cell proliferation vs. survival). [ABSTRACT FROM AUTHOR]